1. Field of the Invention
This invention relates to an improved air nozzle for processing a fiber bundle. More specifically, it relates to an air nozzle suitable for imparting a false twist to a fiber bundle, such as a staple fiber roving or a multifilament yarn. By imparting a false twist to a fiber bundle, part of the staple fibers composing the roving are entangled around a core portion of the roving to form a so-called "fasciated yarn", or, in the case of multifilament yarn, the yarn is texturized during false twisting with the aid of a heat treatment.
2. Prior Art Description
It is a fundamental function of an air nozzle to generate a vortex for twisting a fiber bundle and an auxiliary airstream for sucking the fiber bundle into a yarn passage provided within the air nozzle. An auxiliary airstream is especially very important for fasciated yarn spinning in which the fiber bundle is fed in a ribbon-like form to the air nozzle. Further it is necessary that both the main airstream and the auxiliary airstream be well-balanced so as not to generate a turbulence which may often interfere with the operations of the aforesaid airstreams.
In Japanese Examined patent publication (Kokoku) No. 36-10511, various types of air nozzles are disclosed. Each nozzle is provided with at least a jet, the axis of which is deviated from that of the yarn passage, with the result that a vortex occurs within the yarn passage. However, the nozzle lacks a sucking ability and is not suitable for fasciated yarn spinning.
In Japanese Examined patent publication (Kokoku) No. 50-95528, an air nozzle suitable for fasciated yarn spinning is disclosed in which a narrow channel and a wide channel are arranged in line with one another and are connected by an inclined and, further, are provided with inclined jets opening on the inclined wall. The above-mentioned nozzle has an improved function. However, there is a great difference in function among nozzles of this type because of the difference in the manufacturing accuracy thereof, this difference in manufacturing accuracy being due to the fact that it is very difficult to precisely bore a jet through an inclined wall.
Further, Japanese Unexamined patent publication (Kokai) No. 53-90433 discloses an air nozzle which comprises an inlet opening, an orifice, and a wide channel in series, the last two members being connected by an inclined wall and the wide channel having inclined jets opening in the downstream region of the inclined wall. The nozzle has a drawback in that the edge portion of the fiber bundle is disturbed due to a whirling turbulence within space between the orifice and the wide channel since the fiber bundle, after emerging from the orifice, has to pass through the aforesaid space prior to entering into the constant vortex caused by airstreams ejected from the jets.